Suction catheter

ABSTRACT

Provided is an aspiration catheter which does not require a large-scale device, has a largest possible aspiration lumen, and is sufficiently flexible to track tortuous blood vessels following a guidewire, thereby being easily advanced to a target site to be treated.  
     In the aspiration catheter, the tip of the main shaft is obliquely cut, the distal end of the guidewire shaft is positioned at the distal end of the main shaft or protrudes from the distal end of the main shaft in the distal direction, and the relationships 0.5≦L 2 /L 1  and L 2 −L 1 ≦5 mm are satisfied, wherein L 1  is the length of the obliquely cut portion of the main shaft in the longitudinal direction of the catheter, and L 2  is the length from the proximal end of the guidewire shaft to the distal end of the main shaft.

TECHNICAL FIELD

The present invention relates to an aspiration catheter percutaneouslyand transluminally introduced into the body to remove by aspirationthrombi formed in the internal blood vessels and debris, such asatheromas, released in the blood vessels, by applying a negativepressure from the proximal end of the catheter.

BACKGROUND ART

Conventionally, when stenosis or occlusion occurs in vessels, such asblood vessels, and when blood vessels are blocked by thrombi,angioplasties (e.g., PTA: Percutaneous Transluminal Angioplasty andPTCA: Percutaneous Transluminal Coronary Angioplasty) are commonlyperformed in order to dilate narrowed areas or reopen occluded areas ofblood vessels so that blood flow in the peripheries of blood vessels isimproved. Many angioplasties have been performed in many medicalinstitutions. Furthermore, in recent years, stents have been used tomaintain the dilated state of narrowed areas in many cases.

A balloon catheter for PTA or PTCA is used together with a guidingcatheter and a guidewire mainly for the purpose of dilating a narrowedarea or occluded area of a blood vessel. In an angioplasty using theballoon catheter, first, the guiding catheter is inserted into thefemoral artery and advanced through the aorta, and the tip of theguiding catheter is positioned in the opening of the coronary artery.Then, the guidewire passing through the balloon catheter is advancedbeyond the narrowed area or occluded area of the blood vessel. Theballoon catheter is advanced over the guidewire, and the balloon isinflated while being positioned at the narrowed area or occluded area sothat the narrowed area or occluded area is dilated. The balloon is thendeflated and removed from the body. The application of the ballooncatheter is not limited to treatment of narrowed areas or occluded areasof blood vessels, and the balloon catheter is also useful for many othermedical applications, such as insertion into blood vessels and insertioninto various body cavities and tubular tissue structures.

However, when occlusion is caused by thrombi in the blood vessel, if theoccluded area is dilated by the balloon catheter, there may be apossibility that the thrombi are detached from the inner wall of theblood vessel to occlude peripheral vessels downstream. In the case ofthe narrowed area of the blood vessel in which the lesion contains manyathero-plaques, there may be a possibility that dilation by the ballooncatheter leads to scattering of the athero-plaques (atheromas) toocclude peripheral vessels. When peripheral vessels are blocked asdescribed above, even if the occluded area or narrowed area is dilated,blood is prevented from flowing into the peripheries, resulting inslow-flow or no-reflow.

When such a situation arises, in the coronary artery or the like, it isgeneral practice to wait and see if the blood flow is recovered, but along recovery time is required. According to circumstances, avasodilator, such as nitroglycerin, may be administered to recover theblood flow, or a thrombolytic agent, such as urokinase, may be locallyadministered to dissolve the obstruction. In either case, a longrecovery time is still required. When peripheral vessels are heavilyoccluded to produce poor hemodynamics, an auxiliary procedure, such asintra-aortic balloon pumping (IABP), may be used.

Besides the thrombolytic therapy, a method has been attempted in whichthrombi are mechanically fragmented and a negative pressure issimultaneously applied from the proximal end of the catheter to removethe thrombi from the body.

However, in order to fragment a thrombus at the catheter tip, it is ofcourse necessary to efficiently transmit the mechanical power appliedfrom the proximal end of the catheter to the tip of the catheter.Consequently, in order to enhance the transmission of power in thecatheter shaft, the entire catheter shaft must be composed of a hardmaterial, resulting in difficulty in advancing the catheter to thetarget site in the blood vessel. Furthermore, since a negative pressuremust be applied from the proximal end of the catheter simultaneouslywith the application of mechanical power, a large-scale device isrequired, and thus this method has not become widely used.

On the other hand, the effect of a catheter having a simple structure inwhich thrombi are removed by aspiration from the body by the applicationof a negative pressure from the proximal end has been clinicallyconfirmed. However, the cross-sectional area of the aspiration lumen foraspiration is not sufficiently secured, and only catheters having lowaspiration capability are available. The reason for this is that thecatheter is advanced over the guidewire to the target site in the bloodvessel. Namely, since a guidewire lumen tracking the guidewire isprovided in the aspiration lumen, it is not possible to secure asufficient cross-sectional area of the aspiration lumen.

On the other hand, in a structure in which a guidewire lumen is providedoutside an aspiration lumen, the outer diameter of the aspirationcatheter inevitably increases. Consequently, the inner diameter of theguiding catheter used together increases, resulting in an enormousburden to the patient.

In addition, since any of the guidewire lumens described above usuallyhas a length of about 30 cm from the tip of the aspiration catheter, thecatheter shaft lacks flexibility, resulting in poor insertability intotortuous blood vessels.

DISCLOSURE OF INVENTION

In order to overcome the problems described above, it is an object ofthe present invention to provide an aspiration catheter which does notrequire a large-scale device, secures a largest possible aspirationlumen, and is sufficiently flexible to be advanced to a target sitefollowing a guidewire and to satisfactorily track tortuous bloodvessels.

As a result of intensive research conducted by the present inventors, ithas been found that the problems can be overcome by an aspirationcatheter having the following structure, and thus the present inventionhas been completed.

Namely, an aspiration catheter includes a main shaft having anaspiration lumen disposed therein, the aspiration lumen extending fromthe proximal end to the distal end of the main shaft; a guidewire shafthaving a guidewire lumen disposed therein, the guidewire lumen followinga guidewire, the guidewire shaft being disposed at the distal end of themain shaft; and a hub disposed at the proximal end of the main shaft.The tip of the main shaft is obliquely cut, the distal end of theguidewire shaft is positioned at the distal end of the main shaft orprotrudes from the distal end of the main shaft in the distal direction,and the relationships 0.5≦L2/L1 and L2−L1≦5 mm are satisfied, wherein L1is the length of the obliquely cut portion of the main shaft in thelongitudinal direction of the catheter, and L2 is the length from theproximal end of the guidewire shaft to the distal end of the main shaft.

Preferably, the relationship 2 mm≦L1≦10 mm is satisfied. Morepreferably, the guidewire shaft is provided with a radiopaque marker forconfirming the position of the tip of the main shaft by radioscopy.

Furthermore, at least a proximal portion of the main shaft has aflexural modulus of 1 GPa or more. More preferably, at least a distalportion of the main shaft is applied with a hydrophilic coating.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view showing a tip portion of an aspirationcatheter in an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a tip portion of an aspirationcatheter in another embodiment of the present invention.

FIG. 3 is a side view showing a tip portion of an aspiration catheter inanother embodiment of the present invention.

FIG. 4 is a side view showing a tip portion of an aspiration catheter inanother embodiment of the present invention.

FIG. 5 is a schematic diagram showing a method for evaluating thestrength of aspiration catheters in the present invention.

FIG. 6 is a schematic diagram showing a trackability measurementapparatus for aspiration catheters in the present invention.

FIG. 7 is an enlarged view of a plate including curved portions shown inFIG. 6.

BEST MODE FOR CARRYING OUT THE INVENTION

The embodiments of the catheter of the present invention will bedescribed in detail with reference to the drawings. However, it is to beunderstood that the present invention is not limited thereto.

An aspiration catheter of the present invention includes a main shaft(101, 201, 301, 401, or 501) having an aspiration lumen (102 or 202)disposed therein, the aspiration lumen extending from the proximal endto the distal end of the main shaft; a guidewire shaft (103, 203, 303,403, or 503) having a guidewire lumen (105 or 205) disposed therein, theguidewire lumen following a guidewire, the guidewire shaft beingdisposed at the distal end of the main shaft; and a hub disposed at theproximal end of the main shaft (101, 201, 301, 401, or 501). The tip ofthe main shaft (101, 201, 301, 401, or 501) is obliquely cut. The distalend of the guidewire shaft (103, 203, 303, 403, or 503) is positioned atthe distal end of the main shaft (101, 201, 301, 401, or 501) orprotrudes from the distal end of the main shaft in the distal direction.The relationships 0.5≦L2/L1 and L2−L1≦5 mm are satisfied, wherein L1 isthe length of the obliquely cut portion of the main shaft (101, 201,301, 401, or 501) in the longitudinal direction of the catheter, and L2is the length from the proximal end of the guidewire shaft (103, 203,303, 403, or 503) to the distal end of the main shaft (101, 201, 301,401, or 501). In each of FIGS. 1 and 3, the distal end of the guidewireshaft (103 or 303) is positioned at the distal end of the main shaft(101 or 301). In each of FIGS. 2 and 4, the distal end of the guidewireshaft (203 or 403) protrudes from the distal end of the main shaft (201or 401) in the distal direction. Reference symbol C in the drawingrepresents the obliquely cut portion of the main shaft (101, 201, 301,401, or 501).

Since the guidewire lumen (105 or 205) is disposed at the tip portion ofthe aspiration catheter, it is possible to advance a guidewire, whichthe operator performing an angioplasty is accustomed to using, to theperiphery of the lesion first. Subsequently, the aspiration catheter ofthe present invention can be delivered along the guidewire. Delivery ofthe aspiration catheter along the guidewire also enables treatment ofhighly tortuous portions and bifurcations in the coronary artery andcerebral blood vessels.

By obliquely cutting the tip of the main shaft (101, 201, 301, 401, or501) and attaching the guidewire lumen (105 or 205) thereto, an increasein rigidity of the catheter shaft due to the attachment of the guidewirelumen (105 or 205) can be minimized. However, when L2/L1<0.5, if theaspiration catheter is withdrawn under a situation in which anothercatheter is caught between the tip of the aspiration catheter and theguidewire, the guidewire lumen (105 or 205) of the aspiration catheterbecomes easily broken, which is dangerous. When L2−L1>5 mm, the portionin which the guidewire lumen (105 or 205) is attached to the main shaft(101, 201, 301, 401, or 501) is lengthened, and the rigidity of thecatheter shaft increases greatly. Consequently, trackability of theaspiration catheter in tortuous blood vessels greatly decreases, whichis undesirable. Therefore, the relationships 0.5≦L2/L1 and L2−L1≦5 mmare preferably satisfied.

Furthermore, by disposing the guidewire lumen (105 or 205) only on thetip of the main shaft (101, 201, 301, 401, or 501), it is possible tosecure a largest possible aspiration lumen (102 or 202). At the proximalside of the guidewire lumen, the guidewire is disposed in parallel withthe main shaft.

When the length L1 of the obliquely cut portion C at the tip of the mainshaft in the longitudinal direction of the catheter is less than 2 mm,there is a higher risk of damage to the inner wall of the blood vesselby the catheter tip during the advancement of the catheter through thetortuous blood vessel. If the length L1 exceeds 10 mm, it becomesdifficult to efficiently remove blood clots by aspiration. Therefore,preferably, the relationship 2 mm≦L1≦10 mm is satisfied.

The advantage of the present invention is not particularly restricted bythe method for bonding the guidewire shaft (103, 203, 303, 403, or 503)to the main shaft (101, 201, 301, 401, or 501). Namely, if the guidewireshaft (103, 203, 303, 403, or 503) and the main shaft (101, 201, 301,401, or 501) are composed of materials that can be welded to each other,bonding can be performed by a known method, such as a heat sealingprocess. Alternatively, if the guidewire shaft and the main shaft arecomposed of materials that cannot exhibit sufficient bonding strengthwhen welded, bonding may be performed by a method using an adhesive orthe like. In such a case, the chemical species in the adhesive used isnot particularly limited. For example, a cyanoacrylate, urethane, epoxy,or silicone adhesive is preferably used. The curing mechanism of theadhesive is also not particularly limited. For example, amoisture-curing, two-part curing, or photo-curable adhesive ispreferably used. If the guidewire shaft and the main shaft are composedof materials having poor adhesion properties, surface treatment may beperformed, for example, by oxygen plasma or corona discharge, or using asilane coupling agent.

In the catheter, in order to confirm the position of the tip of thecatheter by radioscopy, the guidewire shaft (103, 203, 303, 403, or 503)is provided with a radiopaque marker (104, 204, 304, 404, or 504) forconfirming the position of the tip of the aspiration catheter byradioscopy. If the radiopaque marker (104, 204, 304, 404, or 504) isprovided on the main shaft (101, 201, 301, 401, or 501), the portionprovided with the radiopaque marker becomes extremely rigid, resultingin a large decrease in the trackability of the entire catheter.Therefore, the radiopaque marker (104, 204, 304, 404, or 504) having aminimally required size is preferably provided on the guidewire shaft(103, 203, 303, 403, or 503).

The advantage of the present invention is not particularly restricted bythe method for attaching the radiopaque marker (104, 204, 304, 404, or504). Namely, the radiopaque marker may be bonded using an adhesive orthe like, physically fixed (by swaging), or attached by any othermethod. In order to minimize damage to the inner wall of the bloodvessel due to the radiopaque marker (104, 204, 304, 404, or 504),preferably, the radiopaque marker (104, 204, 304, 404, or 504) is fixedby swaging and the difference in level between the guidewire shaft (103,203, 303, 403, or 503) and the radiopaque marker (104, 204, 304, 404, or504) is reduced as much as possible.

Furthermore, the radiopaque marker (104, 204, 304, 404, or 504) may becomposed of any material that shows high visibility under radioscopy. Ametal material, such as stainless steel, gold, or platinum, ispreferably used for the radiopaque marker. A gold alloy, a platinumalloy, or the like may also be used.

Furthermore, at least a proximal portion of the main shaft (101, 201,301, 401, or 501) is preferably composed of a high-modulus material witha flexural modulus of 1 GPa or more. By using the shaft composed of sucha high-modulus material, power at the proximal end can be fullytransmitted to the tip of the catheter, and in addition to the pushingforce and the pulling force, the rotating force can be sufficientlytransmitted to the tip.

The main shaft (101, 201, 301, 401, or 501) preferably includes twoshafts, i.e., a proximal shaft and a distal shaft. The distal shaft ispreferably composed of a material having a lower modulus compared withthe proximal shaft. Preferred examples of the material for the distalshaft include polyolefins, polyamides, polyesters, polyurethanes,polyolefin elastomers, polyamide elastomers, polyester elastomers, andpolyurethane elastomers. Preferred examples of the material for theproximal shaft include polyimides, polyamide-imides, polyether etherketones, stainless steel, and nickel-titanium alloys. The method forbonding the distal shaft to the proximal shaft is not particularlylimited, and a known method, such as welding or adhesion, may be used.Preferably, the change in rigidity at the joint between the distal shaftand the proximal shaft is reduced so that rigidity continuously changesin the longitudinal direction of the aspiration catheter.

Preferably, at least a distal portion of the main shaft (101, 201, 301,401, or 501) is applied with a hydrophilic coating. In the aspirationcatheter, if the size of the aspiration lumen (102, or 202) isincreased, the outer diameter of a tube constituting the main shaft(101, 201, 301, 401, or 501) increases, and thereby the sliding frictionof the aspiration catheter with the inner wall of the blood vesselincreases when the aspiration catheter is inserted into the bloodvessel. Therefore, the distal portion of the main shaft (101, 201, 301,401, or 501) which is highly likely to be inserted into tortuous bloodvessels is preferably applied with a hydrophilic coating to reducesliding friction.

The advantage of the present invention is not particularly restricted bythe method for applying the hydrophilic coating and the material for thehydrophilic coating, and the method and the material may beappropriately selected depending on the properties of the main shaft(101, 201, 301, 401, or 501), the guidewire shaft (103, 203, 303, 403,or 503), etc. For example, a hydrophilic polymer, such aspoly(2-hydroxyethyl methacrylate), polyacrylamide, or polyvinylpyrrolidone, is preferably used. Furthermore, by adjusting the thicknessof and the material for the hydrophilic coating in the longitudinaldirection of the main shaft, the sliding friction can be controlled soas to gradually increase or decrease.

The examples and comparative examples of the present invention will bedescribed in detail below.

EXAMPLE 1

A main shaft was composed of two shafts, i.e., a proximal shaft and adistal shaft. As the proximal shaft, a polyimide tube with an outerdiameter of 1.5 mm, an inner diameter of 1.3 mm, and a length of 110 cmwas formed by dip forming using a varnish composed of polyamic acid. Asthe distal shaft, a tube with an outer diameter of 1.5 mm, an innerdiameter of 1.2 mm, and a length of 30 cm was formed by extrusionmolding using a low-density polyethylene tube (LF480M, Japan PolychemCorporation). The diameter of one end of the proximal shaft was reducedby thermal drawing. The portion in which the diameter was reduced wasinserted into the distal shaft and fixed by bonding using a two-partcuring urethane adhesive (Nipporan 4235/Coronate 4403, NipponPolyurethane Industry Co., Ltd.), and the main shaft was therebyobtained. Since the distal shaft was composed of a material with pooradhesion properties, oxygen plasma treatment was performed beforebonding.

The tip of the main shaft was cut with a razor so that the length L1 inthe longitudinal direction of the catheter was 2 mm.

A tube with an outer diameter of 0.6 mm, an inner diameter of 0.42 mm,and a length of 10 mm was formed by extrusion molding using ahigh-density polyethylene (HY540, Japan Polychem Corporation), and aradiopaque marker composed of platinum with an outer diameter of 0.72 mmand an inner diameter of 0.65 mm was fixed by swaging on the center ofthe tube. A guidewire shaft was thereby formed. The guidewire shaft andthe main shaft were placed so that the length L2 was 1 mm (refer to FIG.4), and bonded to each other by heat sealing. During bonding, in orderto secure a guidewire lumen and an aspiration lumen, protective mandrelswere inserted into both shafts.

A hub formed by injection molding using polycarbonate (Makloron 2658,Bayer AG) was fixed on the proximal end of the main shaft by bondingusing a two-part curing urethane adhesive (Nipporan 4235/Coronate 4403,Nippon Polyurethane Industry Co., Ltd.). An aspiration catheter wasthereby produced.

EXAMPLE 2

A catheter was produced as in Example 1 except that L1 was set at 2 mmand L2 was set at 4 mm.

EXAMPLE 3

A catheter was produced as in Example 1 except that L1 was set at 2 mmand L2 was set at 7 mm.

EXAMPLE 4

A catheter was produced as in Example 1 except that the length of theguidewire shaft was set at 35 mm, L1 was set at 10 mm, and L2 was set at5 mm.

EXAMPLE 5

A catheter was produced as in Example 3 except that L1 was set at 10 mmand L2 was set at 15 mm.

COMPARATIVE EXAMPLE 1

A catheter was produced as in Example 1 except that L1 was set at 2 mmand L2 was set at 0.2 mm.

COMPARATIVE EXAMPLE 2

A catheter was produced as in Example 1 except that L1 was set at 2 mmand L2 was set at 10 mm.

COMPARATIVE EXAMPLE 3

A catheter was produced as in Example 3 except that L1 was set at 10 mmand L2 was set at 2 mm.

COMPARATIVE EXAMPLE 4

A catheter was produced as in Example 3 except that L1 was set at 10 mmand L2 was set at 20 mm.

(Evaluation of Bonding Strength Between the Main Shaft and GuidewireShaft)

As shown in FIG. 5, the catheter in each of the examples and comparativeexamples was fastened with fasteners 507 of a tensile tester with amandrel 506 having an arc-shaped end being inserted into a guidewireshaft 503. The fasteners 507 were spaced at 50 mm, and the tensile testwas performed at a rate of 50 mm/min to measure the bonding strengthbetween the main shaft and the guidewire shaft. With respect to each ofthe examples and comparative examples, measurement was performed withn=3, and the mean value was considered as the measured value. Theresults thereof are shown in Table 1. TABLE 1 Evaluation of bondingstrength between the main shaft and guidewire shaft Bonding L1 L2 L2 −L1 strength (mm) (mm) L2/L1 (mm) (N) Trackability Example 1 2 1 0.5 −1.06.2 Satisfactory Example 2 2 4 2.0 2.0 11.8 Satisfactory Example 3 2 73.5 5.0 12.3 Satisfactory Example 4 10 5 0.5 −5.0 6.6 SatisfactoryExample 5 10 15 1.5 5.0 12.1 Satisfactory Comparative 2 0.2 0.1 −1.8 1.7Satisfactory Example 1 Did not pass through bent portion Comparative 210 5.0 8.0 11.5 Kinking Example 2 occurred in catheter Comparative 10 20.2 −8.0 2.9 Satisfactory Example 3 Did not pass through bent portionComparative 10 20 2.0 10.0 11.9 Kinking Example 4 occurred in catheter(Trackability Measurement in Tortuous Blood Vessel)

As shown in FIG. 6, a simulated aorta 603 and a guiding catheter 604were disposed in a tank 601 filled with a physiological saline solutionkept at 37° C., and a hemostasis valve 606 was fixed to the guidingcatheter 604. The tip of the guiding catheter 604 was connected to aplate 602 provided with a simulated coronary artery, and a guidewire 605of 0.014″ (0.3556 mm) was preliminarily passed through the guidingcatheter 604. As shown in FIG. 7, a polyethylene tube 701 serving as asimulated coronary artery was disposed in a plate 702, and thepolyethylene tube 701 included a bent portion 703 and a linear portion704. The bent portion 703 had a radius of curvature of 15 mm, and thelinear portion 704 had a length of 80 mm. The polyethylene tube 701 hadan outer diameter 705 of 5 mm and an inner diameter 706 of 3 mm. Each ofthe aspiration catheters in the examples and comparative examples wasinserted into the guiding catheter 604 from the hemostasis valve 606 andpassed along the guidewire 605, and the operability thereof wasmeasured. The results are shown in Table 1.

In each of Examples 1 to 5 of the present invention, the bondingstrength between the main shaft and the guidewire shaft is sufficientlyhigh at 6.2 N to 12.3 N, and even if another catheter is caught betweenthe tip of the aspiration catheter and the guidewire, it is possible tosafely operate the aspiration catheter without breaking of the guidewirelumen. Furthermore, trackability in the bent portion of blood vessel issatisfactory and good operability is shown. Therefore, these aspirationcatheters are considered to have high performance.

On the other hand, in each of Comparative Examples 1 and 3, althoughsufficient trackability in the bent portion of the simulated bloodvessel is shown, the bonding strength is extremely low at 1.7 N to 2.9N. Therefore, safe operation is not ensured.

In each of Comparative Examples 2 and 4, the bonding strength betweenthe main shaft and the guidewire shaft is high at 11.5 N to 11.9 N, andsafe operation is performed. However, with respect to the trackabilityevaluation using the simulated bent blood vessel, it was not possible toadvance the catheter over the bent portion, and kinking occurred in themain shaft. The reason for this is believed to be due to an increase inrigidity at the joint between the main shaft and the guidewire shaft.

INDUSTRIAL APPLICABILITY

As described above, the present invention can easily provide anaspiration catheter including a main shaft having an aspiration lumendisposed therein, the aspiration lumen extending from the proximal endto the distal end of the main shaft; a guidewire shaft having aguidewire lumen disposed therein, the guidewire lumen following aguidewire, the guidewire shaft being disposed at the distal end of themain shaft; and a hub disposed at the proximal end of the main shaft,wherein the tip of the main shaft is obliquely cut, the distal end ofthe guidewire shaft is positioned at the distal end of the main shaft orprotrudes from the distal end of the main shaft in the distal direction,and the relationships 0.5≦L2/L1 and L2−L1≦5 mm are satisfied, wherein L1is the length of the obliquely cut portion of the main shaft in thelongitudinal direction of the catheter, and L2 is the length from theproximal end of the guidewire shaft to the distal end of the main shaft.In the aspiration catheter, the largest possible aspiration lumen can besecured, and sufficient flexibility is achieved which allows thecatheter to track tortuous blood vessels along the guidewire.

1. An aspiration catheter comprising: a main shaft having an aspirationlumen disposed therein, the aspiration lumen extending from the proximalend to the distal end of the main shaft; a guidewire shaft having aguidewire lumen disposed therein, the guidewire lumen following aguidewire, the guidewire shaft being disposed at the distal end of themain shaft; and a hub disposed at the proximal end of the main shaft,wherein the tip of the main shaft is obliquely cut, the distal end ofthe guidewire shaft is positioned at the distal end of the main shaft orprotrudes from the distal end of the main shaft in the distal direction,and the relationships 0.5≦L2/L1 and L2−L1≦5 mm are satisfied, wherein L1is the length of the obliquely cut portion of the main shaft in thelongitudinal direction of the catheter, and L2 is the length from theproximal end of the guidewire shaft to the distal end of the main shaft.2. The aspiration catheter according to claim 1, wherein therelationship 2 mm≦L1≦10 mm is satisfied.
 3. The aspiration catheteraccording to claim 1, wherein the guidewire shaft is provided with aradiopaque marker for confirming the position of the tip of the mainshaft by radioscopy.
 4. The aspiration catheter according to claim 2,wherein the guidewire shaft is provided with a radiopaque marker forconfirming the position of the tip of the main shaft by radioscopy. 5.The aspiration catheter according to claim 1, wherein at least aproximal portion of the main shaft has a flexural modulus of 1 GPa ormore.
 6. The aspiration catheter according to claim 2, wherein at leasta proximal portion of the main shaft has a flexural modulus of 1 GPa ormore.
 7. The aspiration catheter according to claim 3, wherein at leasta proximal portion of the main shaft has a flexural modulus of 1 GPa ormore.
 8. The aspiration catheter according to claim 4, wherein at leasta proximal portion of the main shaft has a flexural modulus of 1 GPa ormore.
 9. The aspiration catheter according to claim 1, wherein at leasta distal portion of the main shaft is applied with a hydrophiliccoating.
 10. The aspiration catheter according to claim 2, wherein atleast a distal portion of the main shaft is applied with a hydrophiliccoating.
 11. The aspiration catheter according to claim 3, wherein atleast a distal portion of the main shaft is applied with a hydrophiliccoating.
 12. The aspiration catheter according to claim 4, wherein atleast a distal portion of the main shaft is applied with a hydrophiliccoating.
 13. The aspiration catheter according to claim 5, wherein atleast a distal portion of the main shaft is applied with a hydrophiliccoating.
 14. The aspiration catheter according to claim 6, wherein atleast a distal portion of the main shaft is applied with a hydrophiliccoating.
 15. The aspiration catheter according to claim 7, wherein atleast a distal portion of the main shaft is applied with a hydrophiliccoating.
 16. The aspiration catheter according to claim 8, wherein atleast a distal portion of the main shaft is applied with a hydrophiliccoating.